JPH0126553B2 - - Google Patents

Description

Claim 1: A gas-filled cylindrical tube made of a relatively thin electrically insulating material, and a plurality of spaced apart disks within the tube and generally perpendicular to the axis thereof, each disc disposed within the tube. a disk having a central aperture coaxially aligned with the axis of the disk, the aperture defining a central discharge path; and a plurality of cup-shaped members each having a high thermal conductivity. Approximately flat surface, approximately cylindrical rim,
and a cup-shaped member having an opening in the center of the flat surface, the cup-shaped member extending from the central opening of each of the disks to the wall of the tube and passing through the wall of the tube. the disk is attached to the periphery of the opening of each cup, and the distal edge of the rim of each cup is permanently attached along the inner wall of the tube. a fixed laser, further comprising: a device for exciting a gas within the tube; and an optical cavity aligned with the tube.

2. In the laser according to claim 1,
The laser wherein each cup-shaped member has at least one gas return hole between the opening and the rim.

3. In the laser according to claim 2,
Each cup-like member is coaxially aligned with the central opening and further extends at least a portion between adjacent cup-like members and has a radius less than or equal to a radial position to the gas return hole. A laser including a shield having a shielding body.

4. In the laser according to claim 3,
The ring shield extends into the body of the adjacent laser cup.

5. In the laser according to claim 2,
The diameter of the ring shield is laser selected to control the amount of gas pumped within the tube.

6. In the laser according to claim 2,
The size and/or location of the gas return hole may vary depending on the cup-shaped member.

7. In the laser according to claim 2,
The diameter of the ring shield is selected to create a localized change in gas pressure gradient within the tube.

8. In the laser according to claim 1,
A laser in which the anode is secured within the tube by the cup-shaped member such that heat generated from the anode is conducted to and through the tube.

9. In the laser according to claim 1,
The electrically insulating tube is made of ceramic.

10. The laser according to claim 9, wherein the ceramic tube is made of alumina.

11. The laser according to claim 1, wherein the cup-shaped member is made of copper.

12. The laser according to claim 1, wherein the disk is made of tungsten.

13. The laser according to claim 1, wherein the cup-shaped member is fixed by brazing.

14 A gas-filled cylindrical tube made of a relatively thin electrically insulating material and a plurality of thin-walled members made of a material having high thermal conductivity, each coaxially aligned with the axis of the tube. a central opening defining a central discharge path, the central opening of each thin-walled member extending from the central opening to the tube wall;
and a heat conduction path is formed through the tube wall, the distal edge of each thin-walled member is permanently secured along the inner wall of the tube, and each central opening is surrounded by a spatter-resistant material. and further comprising: a device for exciting gas within the tube; and an optical cavity aligned with the tube.

15. The laser of claim 14, wherein each thin-walled member has at least one gas return hole.

16. The laser of claim 15, including a shield coaxially fixed to the thin-walled member to control gas flow within the tube.

17. The laser of claim 14, wherein the cylindrical tube of electrically insulating material is made of alumina, the thin-walled member is made of copper, and the spatter-resistant material is tungsten.

18. A method of manufacturing a gas laser discharge tube comprising assembling within the electrically insulating tube a plurality of spaced apart thermally conductive members each having a central opening generally aligned with the axis of the tube; providing a spatter-resistant disk adjacent to each thermally conductive member, each having an aperture; and tensioning a mandrel passing through a central aperture of the disk to define an optically straight hole. permanently securing the thermally conductive member to the electrically insulating tube, and permanently securing the disc to the thermally conductive member. Method.

19. The method of claim 18, wherein said securing step includes brazing said thermally conductive member to said electrically insulating tube.

20. The method of claim 19, wherein said assembling step includes inserting a braze material between said thermally conductive member and said electrically insulating tube prior to said brazing.

21. The method of claim 20, wherein the step of brazing is accomplished by baking the entire tube assembly while the mandrel is under tension.

22. The method of claim 19, wherein the assembling step comprises: (a) forming a cup of thermally conductive material; and (b) inserting the cup at a distance within the tube. (c) inserting a solder material between the cup-like member and the tube wall; and (d) expanding the rim of the cup-like member toward the inner wall of the tube to open the cup. holding the shaped member in place.

23. A method according to claim 22, wherein a solder material is provided between the disk and the cup.

24. The method of claim 23, wherein at least two of the cup-shaped members are joined to define the centerline of the bore prior to insertion into the tube.

25. The method according to claim 21, wherein the baking step is performed with the mandrel facing vertically.

26. The method of claim 22, wherein the step of assembling includes forming a coaxial shielding ring as part of each cup.

27. The method of claim 19, wherein the thermally conductive member is annealed prior to assembly within the tube.

28. The method of claim 18, including terminating one end of the laser tube with a cathode assembly and the other end with an anode.

29. The method of claim 28, wherein the anode is secured within the tube by attaching the anode to the tube wall by another thermally conductive member.

TECHNICAL FIELD This invention relates to gas lasers, and more particularly to gas ion lasers with improved laser discharge tubes.

BACKGROUND ART There are currently several types of gas ion lasers on the market. One type has a discharge tube that uses a plurality of graphite disks within a gas-filled glass tube. See, eg, US Pat. No. 3,619,810. In other types, thick-walled pieces of beryllium (beryllium oxide BeO) are joined together to form discharge holes. See, for example, US Pat. No. 3,760,213.

Another type of discharge tube is described in US Pat. No. 3,501,714. This patent uses thin-walled, precision-machined ceramic tubing. One of the ceramic materials that has been proposed is alumina (aluminum oxide Al ₂ O ₃ ). The heat generated by the discharge is conducted out of the tube through a series of closely spaced cylindrical sections that heat and expand during tube operation and come into contact with the ceramic tube.

This design has a number of advantages over thick-walled BeO discharge tubes. In a BeO capillary tube with an inner diameter of about 2 mm and an outer diameter of about 1 to 1.5 cm, the heat flow flowing through the beryllium oxide creates a tensile stress on the outer wall of the tube. reaching 10 to 15 percent of its strength. Because alumina has a thermal conductivity that is about one-seventh that of beryllium oxide, and because its stress is inversely proportional to its thermal conductivity, the stress in an alumina capillary of the same size is large enough to break the tube. It can be.

However, relatively thin-walled tubes (ignoring edge effects)
The tensile stress in the circumferential direction and the longitudinal direction in the outer layer is given by the following equation.

1/2△tαε/(1−ν). where Δt is the temperature gradient across the tube wall, α is the coefficient of thermal expansion of the material, ε is the Young's modulus of the material, and ν is Poisson's ratio. If the alumina tube is 1.5 inches (3.81 cm) in diameter
When made to such an extent that the area available for heat flow reduces Δt considerably, the stress can be reduced substantially to the ratio of the outside diameter of the tube.

Alumina tubes can also be made with even thinner walls. The thick walls of beryllium oxide tubes provide structural rigidity and require a large surface area for water cooling. In aluminum oxide tubes, the large outside diameter provides both structural rigidity and available area for water cooling. Stress in aluminum oxide tubing with an inside diameter of 1 1/4" to 1 3/8" and an outside diameter of 1 1/2" to 1 5/8" Calculations amount to 10 to 15% of the breaking strength of aluminum oxide when the same power flows through the tube. Thus, thin-walled aluminum oxide tubes are completely comparable to beryllium oxide in their ability to conductively remove heat without creating stresses in the tubes comparable to the tensile strength of the tubes.

However, the laser tube described in US Pat. No. 3,501,714 has a number of design and manufacturing deficiencies. Many of their shortcomings stem from the use of precision-machined ceramic tubes and disks with tight tolerances that are not permanently bonded to the tube wall.

U.S. Pat. No. 3,501,714 utilizes disk expansion that requires tight tolerances on both surface finish and diameter to ensure a symmetrical and uniform thermal bond between the expanding disk and the ceramic tube wall. describes a gas laser tube. In addition to being expensive and difficult to manufacture, if these tolerances are not met, the expansion of the internal disk, combined with the asymmetric heat flow out of the tube's outer wall, can exceed the tensile strength of the ceramic tube. This results in large tangential stresses. The tight tolerances that must be maintained limit the length of tube that can be machined. In the laser described above, the discharge tube is less than 4 inches (10.16 cm) even though the outer diameter of the tube is about 1.7 inches (4.318 cm). Under conditions of radially symmetrical heat flow, thermal stresses in ceramic tubes result from the inner wall being hotter than the outer wall. The tube therefore expands so that the tangential tensile stress is greater than in the outer wall. Under conditions of symmetrical radial heat flow, the tangential tensile stress in the external wall (ceramic is the weakest in tensile stress) already amounts to about 20% of the tensile breaking stress of the ceramic. It is estimated that even if tight tolerances are maintained, as a result of the asymmetric heat flow conditions that occur, the external ceramic tube tensile stress will be as much as a factor of 5 greater than the stress that would be encountered in the case of symmetrical radial heat flow. This condition could easily rupture the tube.

Furthermore, requiring surface finish tolerances as cited (16RMS or more on the outside of the disk, 32RMS or more on the surface finish of the inside wall of the alumina tube) limits the effective surface area available for heat flow from the tube wall.

The laser described in Patent No. 3,501,714 relies on the use of a thick disk to maximize the surface area available for heat transfer between the gas discharge and its outer ceramic encapsulation tube. This fact, and the poor thermal contact between the inner disk and the outer ceramic encapsulation tube, presents a large impedance (resistance) to gas flow within the laser in several ways. First, thick disks require the use of cylindrical channels through which the gas flow passes, and thick disks create a greater impedance for the gas flow. Second, the disk temperature is higher, creating a greater gas flow impedance.

DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide an improved gas laser and method of manufacturing the same.

Another object of the invention is an improved discharge tube,
The purpose is to provide one particularly suitable for use in ion lasers.

Another object of the invention is to provide an ion laser with an improved gas discharge tube that can be manufactured using low tolerance components.

Another object of the invention is to provide a gas ion laser that is robust and highly reliable.

Another object of the invention is to provide a gas ion laser with a discharge tube that is effective in conducting heat from the discharge path.

Another object of the invention is to provide a gas ion laser tube with a device for controlling the amount and direction of gas pumping within the tube.

According to the present invention, gas lasers, particularly gas ion lasers, can use thin-walled, relatively low error tolerance ceramic discharge tubes such as alumina. Heat from the electrical discharge is effectively transferred to the ceramic tube through the use of a thin-walled cup member permanently bonded to the inside wall of the ceramic tube.

The discharge cross-section is determined by an aperture in the cup member or in a spatter-resistant disk coaxially fixed to the cup member. A gas return hole is provided at the periphery of the cup member.

Using this structure, heat generated by plasma discharge is conducted from the cup members and the ceramic encapsulated tube, but the temperature difference between the center of the cup and the outer wall of the ceramic tube is small. This small temperature difference is due to the tight bond between the cup and the ceramic tube. More specifically, these internal members will deform and conform to the ceramic tube even if either of them has insufficient roundness or irregularities in surface finish. Additionally, by brazing, soldering, etc., a permanent metal contact can be provided between the inner cup and the outer ceramic wall, which provides a high thermal conductivity between the two.

As a result of using these methods, the required error tolerances for the internal and external parts are significantly reduced.
This also allows the fabrication of very long structures without requiring machining of these parts. Preferably the cup member supporting the disc defining the hole is made of thin walled copper.

Copper is a good material to use for these disks. The reason for this is that copper, when properly annealed, is ductile, easily expands into contact with walls, and has high conductivity. As a result, the thin section between the central hole and the wall provides a small temperature gradient and keeps the temperature rise in the internal part low without thickening the internal part. There is no need to leave room for thermal expansion as in the laser design in US Pat. No. 3,501,714.

The thin wall member above has several advantages over the thick wall used in the laser design of US Pat. No. 3,501,714. First, the thin walls, as mentioned above, allow for easier cup deformation to fit the inner diameter of the outer ceramic tube without any tolerances for either circumferential or surface finish tolerances. This provides a uniform thin space that can be uniformly wetted by capillary action of the solder or solder material, which provides a thermal bond between the cup and the ceramic tube. By combining it with a low-precision ceramic tube, a laser tube can be manufactured relatively easily.

Second, the thin-walled cup provides a large volume for gas storage within the tube. The effect of this is that good operation is obtained without the need for external balancing tanks to minimize pressure changes in the tubes during start-up or when changing from one level to another.

Third, a thin-walled cup, in combination with a shield, is large, cool, and therefore highly gas conductive (low pressure drop), and allows a hole in the periphery of one disk to pass through the periphery of the next disk. By providing a path to the upper hole, a low pressure gradient can be maintained along the tube.

According to another aspect of the invention, each cup member is provided with an axial ring or shield so that the gas near the ceramic tube wall is kept at a lower temperature so that it is trapped within the tube. The amount of gas delivered is increased. This shield assists in minimizing or controlling gas pumping within the tube.

Another feature of this laser design is the anode. This anode is mounted like the other internal tube members. The heat generated at the anode is therefore directly conducted by conduction through the ceramic encapsulation tube. The anode has no electrical contact with the cooling water, eliminating electrolysis. Therefore, water resistivity and mineral abundance do not affect tube life.

[Brief explanation of drawings]

FIG. 1 is an exploded cross-sectional view of an improved gas ion laser according to the present invention.

2 is a cross-sectional view of the cup member and shield used in the laser of FIG. 1; FIG.

FIG. 3 is a partial cross-sectional view of the cup member of FIG. 2 when placed within the ceramic tube during assembly.

FIG. 4 is a perspective view of the hard solder clamp shown in FIG. 3.

FIG. 5 is a plan view of the insertion and expansion tool used to assemble the improved laser of the present invention.

6 is a partial cross-sectional view of a portion of the tool of FIG. 5; FIG.

FIG. 7 shows the cup member after it has been inserted into the ceramic tube.

FIG. 8 shows an apparatus for manufacturing spatter-resistant disks with defined holes.

FIG. 9 is a perspective view of the disk before assembly.

FIG. 10 is a plan view of a hard solder ring used to braze the disk of FIG. 9 to the cup member.

Figure 11 shows the first spot welded to the disk.
It is a figure which shows the hard soldering ring of figure 0.

FIG. 12 is a diagram showing an assembly of a cup and a disk in a discharge tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded cross-sectional view of an improved gas ion laser 10 according to the present invention. The laser 10 is filled with an active gas such as argon or krypton,
and includes a discharge tube 12 having an axis 14 aligned with mirrors 16, 18 (shown schematically) to form an optical cavity. The discharge tube 12 is a gas-filled cylindrical tube, and the discharge tube 12 is surrounded by a water jacket 20 (also shown in outline). Water enters the jacket at inlet 22, absorbs heat, and exits at outlet 24. Surrounding the water jacket is a solenoid, not shown, which confines the discharge plasma in a known manner.

The discharge tube 12 includes a thin-walled ceramic tube 26, a cathode assembly 28, an anode 30, and end window assemblies 32, 34.
including. The latter window assemblies each have cathode assemblies 28
and is fixed to a nickel window support tube 36 to the anode 30.

Cathode assembly 28 includes two connections 38, 40 connected to a power source (not shown) and connected to a helical cathode 42. A heat shield 44 is provided to prevent radiation and sputtering from the cathode 42 from entering the area near the window 32.

The plasma discharge path and plasma discharge cross-sectional area are determined by openings or holes 46 provided in a plurality of disks 48. Disk 48 is preferably made of a spatter resistant material. In FIG. 1, the entire discharge tube 12 is not shown, so only seven disks are shown. In one actual embodiment, more than 50 such disks are used.

The disk 48 is a cup-shaped member 5 which is a thin-walled member.
It is joined to the periphery of the opening 49 of No.8. They are made from materials that are good thermal conductors and are malleable, such as copper. A rim 52 of cup member 50 is permanently bonded to the inner wall of ceramic tube 26. A gas return hole 54 is provided between the rim 52 of the cup member 50 and the opening 49. Heat generated by the plasma discharge is transferred from the disk 48 and cup member 50 to the ceramic tube 26.
is rapidly conducted through the tube walls, from which heat is carried away by the water coolant.

A cylindrical shield (ring) 56 is coaxially mounted or formed on each of the cup members 56. These shields maintain the gas within region 58 at a relatively low temperature. Each shield 56 has a cup 50
It is cooled by heat conduction to the tube wall of the ceramic tube 26 through the tube. If there is no shield 56, the area 58
The gas inside is heated by conduction of discharge heat. If this happens, less important gas atoms will be stored in the tube and it will take a longer time to reach equilibrium after switching on. The reason is that gas must move from the gas return hole to the anode and cathode regions before a suitable operating pressure is achieved in the discharge region. Shielding body 56
is in place, gas need only move from region 60 to region 58 to establish equilibrium operating conditions.

Gas pumping may occur by accelerating ions through the gas return hole 54 under the influence of an electric field in the vicinity of the gas return hole. The shield 56 provides a surface for recombination and a channel 62 for ions to migrate into the region 58.
The number of ions in region 58 is minimized by providing only 1.

It is well known that all ions in the discharge region fall freely to the walls of the pore (in theory,
When a low-pressure discharge occurs in a continuous pore (as described as the Langmiur-Tonks model), gas pumping is directed toward the anode at low currents;
At high currents, it faces the cathode. If the confinement structure is in an area without nearby walls, pumping is always directed towards the cathode. Therefore, by appropriately choosing the diameter of the shield 56, it is possible to ensure that there is no net pumping under the maximum discharge current for which the system was designed. This is an important consideration in long ion lasers where it is difficult to provide sufficient detours for internal gas return in the conventional manner.

The direction of gas pumping by the discharge can be controlled by the shape and diameter of the holes and shield 56, so that the tube can be made to vary at different sections along the tube. It is therefore possible, for example, to have anodic pumping in one region and cathodic pumping in another region. This provides a pressure gradient within the tube that minimizes the growth of plasma oscillations while providing an overall zero or small pressure difference. If the gas return hole is significantly enlarged from a diameter that is slightly smaller than the hole diameter, discharge can also pass through the gas return hole. However, if the diameter and/or location is changed, the discharge will probably not pass through these bypass holes. This is because the path of this structure must be strained considerably for this to occur. This forced path also includes regions where the discharge occurs perpendicular to the magnetic field rather than parallel to it. This tends to drive the discharge towards the wall and increase the discharge potential per unit length.

Alumina tubing 26 is available from manufacturers such as Coors and McDonnells and is
It is a standard item with a wall thickness of 1.50 inches (3.81 cm) and 0.125 inches (0.3175 cm). Inner cylinder tolerance is ±0.05 inch (0.127
cm) and inch straightness from 0.06 to 0.12 inch (0.1524 to 0.3048 cm). Using standard self-jigging and auxiliary-jigging methods in combination with series brazing to produce perforated tubes as shown in Figure 1 would be a straightforward method, but would require significant changes in internal diameter and straightness. Tolerances preclude their use.

It is clear that ceramic tubes with small tolerances regarding internal diameter and straightness are very expensive. The following techniques are "standard tolerances" available:
It can be used to manufacture the ion laser perforated tube of FIG. 1 using the ceramic tube of FIG.

As shown in FIG. 2, a copper cup member 50 is formed from an OFHC copper sheet by drawing. The shield 56 is then joined to the cup 50, for example by brazing.

Copper cup 50 and ceramic tube 26 shown in FIG.
A ring-shaped brazing material 64 (Fig. 4) is placed between
is placed. One suitable brazing material is "Tiscusil." This material is
A copper-silver fusion with a small addition of titanium used in a paste that forms a bond between ceramic and metal under a process called active metal processing. In this process, the titanium depletes the ceramic material so that a ceramic-to-metal bond is achieved in a single operation. This eliminates the need for prior art ceramic metallization methods, for example by the known molymanganese method or other methods.

It has been found desirable to provide the cup 50 with a circumferentially extending groove 66 along the edge surface thereof. This groove receives a lip 68 formed in the ring of brazing material. The purpose of the lip and groove combination is to prevent the brazing material from shifting during the brazing operation. This ensures clean copper to ceramic contact at the corners of the cut rim.

FIGS. 5-7 show how the individual cup members 50 expand against the inner wall of the ceramic tube 26 so as to form a secure mechanical bond prior to brazing. ing. Ceramic tube 2
6 is supported on a carriage 70 which can be moved in parallel along rails 72. Within tube 26 is a floating mandrel 74 . An expansion tool 76, including an elongated portion 78 and an expansion head 80, is secured parallel to rail 72. Copper cup 50 is first inserted onto inflation head 80. Carriage 70 is then moved toward inflation tool 76 as shown in phantom while centering cup 50 within tube 26.

A suitable device, such as a hydraulic pump (not shown), serves to drive the piston 79, which resists a plurality of circumferentially disposed fingers 84 within the cup-like member 50. Then push outward and spread out the elastic ring (Fig. 6) that had been packed in until then. These fingers deform the rim 52,
And, it is forcibly brought into firm contact with the ceramic tube 26. In this position (FIG. 7) the tube is ready for subsequent brazing operations.

The copper cups 50 are annealed before being inserted into the tube 26 to minimize the force required to expand them and to make them better compatible with the ceramic tube 26. This is desirable since the inner diameter of the tube is slightly more distorted than the inner diameter.

Plating the disk 48 prior to brazing will now be described. Initially, tungsten disk 48 is screwed onto mandrel 86 inside O-ring 90 (FIG. 8) and spaced apart by metal spacer 88. This assembly is then nickel plated to a thickness of 0.0005 to 0.0010 inches (0.00127 to 0.00254 cm). An O-ring 90 covers the inner area of the disk and a metal spacer 88 provides electrical contact to the disk. This coating then prevents the surface from being wetted by the solder material. A molded disk having a nickel coated outer region 92 is shown in FIG.

After plating, the disk 48 is fired in hydrogen at 900° C. for 10 minutes. This anneals the nickel plating and improves the nickel-tungsten bond. A hard solder ring 94, shown in FIG. 10, is formed from 0.030 inch (0.0762 cm) diameter Nikulsi-3 wire available from Western Gold and Platinum Company. This hard solder ring is then spot welded to one side of the tungsten disk 48 at point 96 as shown in FIG.

Here, the tube assembly sequence will be explained. The cup 50 is first placed on the inflation tool 76 and the tool is fully inflated to hold the cup 50 in place. A hard solder foil ring 64 is placed around the cup 50 and the carriage and tube are moved until the cup is in the proper position within the tube 26. The tungsten mandrel 74 is free to float within the tube 26 and travels with the tube on the carriage 70 so as to slide into the bore of the expansion tool. After the cup 50 is inflated, the pressure on the elastic body 78 is relieved and the carriage and tube combination is then removed from the inflation tool. Then the 12th
A tungsten disk-hard ring assembly slides over the mandrel as shown. This procedure is repeated, installing alternately cups 50 and disks 48, until the hole is completed.

In practice, the first and last tungsten discs 48, which match the mandrel diameter, can be pre-brazed to their respective copper cups 50 using a higher temperature hard solder alloy. These two discs define the centerline of the hole.

Prior to brazing, the tube-bore assembly with the mandrel attached is placed vertically in a vacuum furnace with end "B" (FIG. 12) facing upward. The mandrel 74 is held taut at one end and pulled taut at the opposite end during the brazing cycle. This ensures that all intermediate discs 48 are aligned to form optically straight holes after brazing.

A "transition" section consisting of one or more sections with progressively larger disc holes 49 is provided at one or both ends. In this case, the first and last "core size" disks and the larger size disks outside these are all pre-brazed.

Copper tends to expand more than ceramic as the assembly is heated. The reason is that their coefficients of thermal expansion are different. As a result, when the brazing temperature is achieved, the cup 5 is in the tube 26.
0 is very tightly engaged. The copper is well annealed at the brazing temperature because it will stretch in response to the stresses created by differential thermal expansion during the cooling period and will not dislodge from the ceramic at the brazing point.
This is desirable.

The step of aligning the "floating" disk onto a tensioned straight mandrel is very important for producing strictly optically straight holes in ceramic tubes, which have very low tolerance requirements. "Very straight pores" may be interpreted as having an overall straightness of less than 10% of the pore diameter.

Cathode assembly 28 is housed within a copper container 29, which must form a hermetic seal with tube 26. The same expansion-brazing method described above is used to form this joint. Brazing is necessary on the inside of the tube to obtain good thermal conductivity between the cup and the tube wall. At the ends a vacuum-sealed joint is likewise necessary, and after expansion the cup may be pressed more closely against the wall by a chisel-shaped tool so that the cup conforms to small irregularities in the tube wall. This provides better vacuum sealing.

This same manufacturing method is used for mounting the anode 30. The resulting shape has important advantages. Anode 30 is mounted by a copper cup 51 similar in design to cup 50. As a result, the heat generated by the anode is conducted out of the tube through the cup 51. The anode is thus cooled without any electrical contact with the cooling water. The anode is manufactured by U.S. Patent No.
It is electrically isolated from the rest of the tube without the use of an insulating varnish between the anode and the tube 26 as in No. 3,501,714. Also, the conductor (not shown) is drawn out of the tube 26 without passing through the wall of the tube.

Another technique to provide a highly spatter resistant material is to deposit tungsten onto the central region of the copper cup 50 by known methods. In this case, of course, the above expedient of sliding the tungsten disc 48 to center it on the mandrel cannot be applied. However, a straight hole can be created by using an insert with a pin to hold the tungsten in the center of the tube determined by external mechanical criteria.
Still achievable. The copper cup is then expanded against the tube wall so that the tungsten plated copper center portion remains aligned and the copper cup rim conforms to the tube wall.

Another method for attaching the copper cup 50 to alumina is as follows. Alumina tube 26 pre-metallized with MoMn or otherwise metallized
The copper cup may be pulse brazed in place by a pulse induction heating device that heats the cup 50 and the ceramic metallized periphery to melt the solder when the cup is expanded into contact with the wall. . As a result of cooling the alumina wall after the pulse ends, the solder is cooled below its melting point.
The tool can be withdrawn immediately with the copper cup brazed in place. This method is preferred when permanent magnets are used inside the tube. This is because this method is one way to attach copper cups at low temperatures without causing the magnet to lose its magnetism.

Since the tubes operate at relatively low temperatures, interruptions in water cooling will not boil the water remaining in the cooling jacket. Calculations indicate that the heat stored within the tube is insufficient to even raise the perforated tube 26 to the boiling point of water. Air cooling tubes are also possible with this laser design method. (In that case) cooling fins are attached directly to the outer surface of the alumina tube 26.

In one actual example, the following dimensions were used:

Katsupu (50) Thickness 0.0762cm Diameter of opening (49) 0.7874cm Outer diameter 2.8575cm Brazing ring (64) thickness 0.00508cm Disc (48) Hole (46) Diameter 0.2794cm Outer diameter 1.27cm Thickness: 0.0254cm Shield (56) Outer diameter 1.905cm Inner diameter 1.5875cm